In one typical kind of clutch engagement/disengagement system, a clutch disengaging unit operates by a sleeve mounted on a guide (e.g., on the output shaft of the transmission). This sleeve can be moved to cause a clutch element to shift between an engaged and disengaged position. For instance, where the clutch element is a friction plate of a plate or disk clutch, movement of the sleeve on the guide can deform a diaphragm spring of the clutch such that pressure plates are disengaged from corresponding friction linings on the clutch disk.
A simple mechanical linkage can serve as the mechanism by which the sleeve is moved to shift the clutch element between the engaged and disengaged positions. Specifically, in one common configuration shown in FIGS. 1 and 2, a clutch linkage 100 can include a control shaft 102 on which two separate arms 104 are attached for pivoting movement with control shaft 102. Each of arms 104 can include an inward-facing protrusion 106 (i.e., facing towards the other of arms 104). Protrusions 106 can engage a sleeve 108 to move sleeve 108 between the engaged and disengaged positions. Specifically, for example, sleeve 108 can include a groove 110 in which protrusions 106 can be disposed or inserted. As a result, when control shaft 102 is rotated, arms 104 move sleeve 108 along a guide 112 to engage or disengage a clutch element 150, such as a pressure plate of a disk clutch.
Although this simple linkage arrangement can be used for transmitting the motion of control shaft 102 to clutch element 150, the effectiveness of such a component can be compromised by certain aspects of the design. For instance, because arms 104 are independently mounted on control shaft 102, small differences in the positions of arms 104 relative to control shaft 102 can exist because of machining tolerances and the precision of assembly and installation of the components. As a result, it is difficult to ensure that both of arms 104 engage their respective protrusions 106 with groove 110 of sleeve 108 at the same instant and to the same extent. This uneven application of force can lead to uneven wear upon clutch linkage 100 and sleeve 108, sleeve 108 can tend to jam or at least offer a very pronounced resistance to axial movement along guide 112, and pressure can be applied unevenly to clutch element 150, which can reduce the operating life of any bearings connected therewith.
These drawbacks can impede the smooth operation of the clutch and reduce the useful life of sleeve 108 and/or guide 112, especially if sleeve 108 is made of a synthetic material (e.g., plastic). Additional drawbacks of such declutching device designs include the initial cost of manufacture of multiple component parts that make up clutch linkage 100, and installation of all of the parts individually can be time consuming. As a result, it would be desirable for a new declutching device that can operate more consistently than current designs without increasing the cost of manufacture or installation.